As an input media, a touch panel (TP) is integrated together with a display panel as a touch screen. The touch panel is able to work importantly in a field of display.
Particularly, a capacitance touch panel has got a lot of attention at present because of its high sensitivity. A mutual-capacitance touch panel is favored in people relying on its advantages such as high sensitivity and a multi touch. The capacitance touch panel comprises an out-cell touch panel and an in-cell touch panel. The in-cell touch panel is a touch panel integrating the TP into a Liquid Crystal Display (LCD) panel. The in-cell touch panel has become a research focus by people because it has a low manufacture cost, a good light transmittance, a thin thickness of array, etc.
A basic operation principle of the mutual-capacitance touch panel would be discussed below. FIG. 1 is an exemplary view illustrating a structure of an existing touch panel. A touch driving electrode of the mutual-capacitance touch panel decides an X-direction coordinate of a touch point, and a touch sensing electrode decides a Y-direction coordinate of the touch point. A touch driving voltage is applied at the touch driving electrode side, and a constant voltage is applied at the touch sensing electrode. When the touch point is detected, the touch driving electrodes in the X-direction are scanned progressively, and signals on each row of the touch sensing electrodes are read when each row of the touch driving electrodes are scanned. Intersections among the each row and each column can be scanned by one round of scanning, and total X*Y signals are scanned. Such touch positioning detection manner may determine coordinates of a plurality of points exactly, therefore it may realize a multi touch.
When a finger touches the touch panel, a part of current in a circuit may flow into the finger, which is equivalent to a change of a value of the mutual-capacitance between the touch driving electrode and the touch sensing electrode, and a slight change in the current caused by the mutual-capacitance may be detected at a touch point detection circuit end. Because both of the touch driving electrodes and the touch sensing electrodes are disposed in the liquid crystal display panel, a distance between the TP structure and the common electrode of the LCD is small, and a parasitic capacitance between the touch driving electrode/touch sensing electrode and the common electrode is very huge, such that a noise in the LCD has a great effect on the TP; therefore the current signal detected by the touch point detection circuit is almost annihilated into the noise, thus a touch effect is very poor, which may even lead to the touch panel unable to operate normally.
Furthermore, although some of the existing touch panels multiplex electrode lines which have existed on the LCD, for example, the common electrode lines or the gate lines, a resistance would be large when the sensing electrodes utilize each electrode line, which causes a low sensitivity of the touch.